Mars rover: Is all this really necessary?

By Thom Patterson, CNN

Updated 9:40 AM ET, Tue August 7, 2012

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Photos:Photos: Exploring Mars

Exploring Mars – Water-ice clouds, polar ice and other geographic features can be seen in this full-disk image of Mars from 2011. NASA's Mars Curiosity Rover touched down on the planet on August 6, 2012. Take a look at stunning photographs of Mars over the years. Check out images from the Mars rover Curiosity.

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Exploring Mars – This image was captured in 1976 by Viking 2, one of two probes sent to investigate the surface of Mars for the first time. NASA's Viking landers blazed the trail for future missions to Mars.

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Exploring Mars – The Valles Marineris rift system on Mars is 10 times longer, five times deeper and 20 times wider than the Grand Canyon. This composite image was made from NASA's Mars Odyssey spacecraft, which launched in 2001.

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Exploring Mars – The Nili Fossae region of Mars is one of the largest exposures of clay minerals discovered by the OMEGA spectrometer on Mars Express Orbiter. This image was taken in 2007 as part of a campaign to examine more than two dozen potential landing sites for NASA's new Mars rover, Curiosity, also known as the NASA Mars Science Laboratory.

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Exploring Mars – NASA's Mars Phoenix Lander descends to the surface of Mars in May 2008. Fewer than half of the Mars missions have made successful landings.

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Exploring Mars – Phoenix's robotic arm scoops up a sample on June 10, 2008, the 16th Martian day after landing. The lander's solar panel is seen in the lower left.

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Exploring Mars – In 2006, NASA's Mars Exploration Rover Spirit captured a 360-degree view known as the McMurdo panorama. The images were taken at the time of year when Mars is farthest from the sun and dust storms are less frequent.

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Exploring Mars – The European Space Agency's Mars Express captured this view of Valles Marineris in 2004. The area shows mesas and cliffs as well as features that indicate erosion from flowing water.

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Exploring Mars – This view is a vertical projection that combines more than 500 exposures taken by Phoenix in 2008. The black circle on the spacecraft is where the camera itself is mounted.

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Exploring Mars – A portion of the west rim of the Endeavour Crater sweeps southward in this view from NASA's Mars Exploration Rover Opportunity in 2011. The crater is 22 kilometers (13.7 miles) across.

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Exploring Mars – A photo captured by NASA's Mars Global Surveyor in 2000 offers evidence that the planet may have been a land of lakes in its earliest period, with layers of Earth-like sedimentary rock that could harbor the fossils of any ancient Martian life.

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Exploring Mars – A U.S. flag and a DVD containing a message for future explorers of Mars, science fiction stories and art about the planet, and the names of 250,000 people sit on the deck of Phoenix in 2008.

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Exploring Mars – A rock outcrop dubbed Longhorn and the sweeping plains of the Gusev Crater are seen in a 2004 image taken by the Mars Exploration Rover Spirit.

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Exploring Mars – Although it is 45 kilometers (28 miles) wide, countless layers of ice and dust have all but buried the Udzha Crater on Mars. The crater lies near the edge of the northern polar cap. This image was taken by NASA's Mars Odyssey Orbiter in 2010.

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Exploring Mars – NASA's Opportunity examines rocks inside an alcove called Duck Bay in the western portion of the Victoria Crater in 2007.

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Exploring Mars – Pictured is a series of troughs and layered mesas in the Gorgonum Chaos region of Mars in 2008. This photo was taken by Mars Orbiter Camera on the Mars Global Surveyor.

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Exploring Mars – An image captured in 2008 by NASA's Mars Reconnaissance Orbiter shows at least four Martian avalanches, or debris falls, taking place. Material, likely including fine-grained ice and dust and possibly large blocks, detached from a towering cliff and cascaded to the gentler slopes below.

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Exploring Mars – This 2008 image spans the floor of Ius Chasma's southern trench in the western region of Valles Marineris, the solar system's largest canyon. Ius Chasma is believed to have been shaped by a process called sapping, in which water seeped from the layers of the cliffs and evaporated before it reached the canyon floor.

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Exploring Mars – Pictured is the Martian landscape at Meridiani Planum, where the Mars Exploration Rover Opportunity successfully landed in 2004. This is one of the first images beamed back to Earth from the rover shortly after it touched down.

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Exploring Mars – An image from the Mars Global Surveyor in 2000 shows potential evidence of massive sedimentary deposits in the western Arabia Terra impact crater on the surface of Mars.

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Exploring Mars – The Mars Reconnaissance Orbiter captures a dust devil blowing across the Martian surface east of the Hellas impact basin in 2007. Dust devils form when the temperature of the atmosphere near the ground is much warmer than that above. The diameter of this dust devil is about 200 meters (650 feet).

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Exploring Mars – Soft soil is exposed when the wheels of NASA's Mars Exploration Rover Spirit dig into a patch of ground dubbed Troy in 2009.

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Exploring Mars – An image from NASA's Mars Reconnaissance Orbiter shows the floor of the Antoniadi Crater in 2009.

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Exploring Mars – The larger of Mars' two moons, Phobos, is seen in 2008 from the Mars Reconnaissance Orbiter.

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Exploring Mars – Earth and the moon are seen in 2007 from the Mars Reconnaissance Orbiter. At the time the image was taken, Earth was 142 million kilometers (88 million miles) from Mars.

Hey Mars! We're back! Hope you don't mind if we cruise around in our scientific SUV to grab some historic data and snap some breathtaking images. Oh, and we might do some Martian doughnuts in your front yard.

Now that the Mars rover Curiosity is safely parked, NASA's unmanned planet crawler appears ready to roll. A car salesman would have a ball selling this beauty. It's loaded with an array of sophisticated cameras, a "rocker bogie" suspension, a robotic arm, 2 gigs of flash memory, a rock-vaporizing laser (!!!!) and a plutonium-fueled power system. It operates by remote control from millions of miles away and has a blazing top speed of 1.5 inches per second.

Sticker price (including delivery): $2.6 billion.

During its expected lifespan of 23 months, all this cool hardware could help solve big mysteries: Has life ever existed on Mars? What can Mars tell us about our own planet? Can we benefit from Martian resources?

But there are less romantic questions swirling around the fourth rock from the sun: Is the price tag really worth it? Who will pay for the first manned mission to Mars? Could manned space missions be replaced by robotic exploration?

"Back when the Internet was young, it was the largest Internet event in the history of that medium," Curiosity team member James Bell told CNN on Monday. The little rover found clues suggesting that Mars once had a thicker atmosphere and liquid water. Sojourner and its parent spacecraft Pathfinder cost $265 million (PDF).

"Later, in 2004, when the Spirit and Opportunity rovers landed, it became one of the largest worldwide Internet sensations," said Bell, who also worked on that mission. "It slammed NASA's website." The rovers scored several discoveries including evidence of an ancient wet environment on Mars. Price tag for Spirit and Opportunity: $800 million (PDF).

Nowadays -- at least for some space travel fans -- Martian robots aren't so cool anymore. Curiosity "is just another box with wheels on Mars," says CNN commenter It_could_always_be_worse. "Develop useful technology -- not this shooting of boxes with wheels all over the place. SEND PEOPLE, and I will be proud."

But first, mission planners need more information about the Martian surface so they can choose the best landing sites.

"We don't want astronauts to be surprised," says Bell. Robot missions, such as Surveyor, preceded the Apollo moon landings, and these Martian probes are performing similar tasks.

Putting a monetary value on space exploration is impossible, experts say, because there are too many unanswered questions, such as whether Mars, the moon or asteroids hold precious minerals, water and cheap energy resources that could be mined and brought back to Earth.

"The reason to send humans will be because we have to," Bell says. "If some things can be done by robots, they should be done by robots. But sending a drill rig to Mars or Jupiter's moon Europa to tap into an aquifer that may have living organisms in it -- those kinds of things will require people."

Then there's the unknown value of newly discovered knowledge. Scientists want to know what Mars can tell us about our own planet's climate and geology. That knowledge, experts say, could help solve difficult environmental problems on Earth.

"It's human nature to explore," says Bell. "By going to difficult or dangerous places, we carry the rest of our species along with us. These stories become part of part of our culture, part of our heritage, part of our shared need to explore the worlds around us. it's a human endeavor that is part science, part inspiration."

But big questions remain: How would NASA pay for development of a landing vehicle? Or a vehicle for astronauts to travel on the Martian or lunar surface? Or how would it develop an astronaut habitat suitable for the months it would take to travel to Mars or to asteroids?

NASA's proposed budget for 2013 is $17.7 billion -- $59 million less than 2012 (PDF). It includes a "lower cost program" for unmanned missions to Mars (PDF). For perspective, the Mars rover's $2.6 billion price tag equals about 14.7% of NASA's proposed 2013 budget.

However, the budget also calls for more money for manned deep space programs, including almost $3 billion for Orion and the Space Launch System.